Light emitting device having a dam surrounding a light emitting region

ABSTRACT

A light emitting device includes: a base substrate; a plurality of unit regions provided on the base substrate; a barrier disposed at a boundary of the unit regions to surround each of the unit regions; a dam disposed in each of the unit regions to be spaced apart from the barrier; a first electrode provided in each of unit light emitting regions surrounded by the dam; a second electrode disposed in each of the unit light emitting regions, the second electrode of which at least one region is provided opposite to the first electrode; and one or more LEDs provided in each of the unit light emitting regions, the one or more LEDs being electrically connected between the first electrode and the second electrode.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/440,906 filed on Jun. 13, 2019, which is acontinuation application of U.S. patent application Ser. No. 15/813,807filed on Nov. 15, 2017, which claims priority to Korean PatentApplication No. 10-2016-0152148, filed on Nov. 15, 2016, in the KoreanIntellectual Property Office, the entire disclosures of which areincorporated by reference herein.

BACKGROUND 1. Field

An aspect of the present disclosure relates to a light emitting deviceand a fabricating method thereof.

2. Description of the Related Art

Light emitting diodes (hereinafter, abbreviated as LEDs) exhibitrelatively satisfactory durability even in poor environmental conditionsand have excellent performance in terms of lifespan and luminance.Recently, studies for applying such LEDs to various light emittingdevices have been actively conducted.

As a part of such studies, there has been a technique for fabricating amicro LED that is small to a degree of micro or nano scale using aninorganic crystal structure, e.g., a structure in which a nitride basedsemiconductor is grown. For example, the LED may be fabricated in a sizesmall enough to constitute a pixel of a self-luminescent display panel,and the like.

SUMMARY

Embodiments provide a light emitting device that includes a LED and hasuniform luminance characteristics, and a fabricating method of the lightemitting device.

According to an aspect of the present disclosure, there is provided alight emitting device including: a base substrate; a plurality of unitregions provided on the base substrate; a barrier disposed at a boundaryof the unit regions to surround each of the unit regions; a dam disposedin each of the unit regions to be spaced apart from the barrier; a firstelectrode provided in each of unit light emitting regions surrounded bythe dam; a second electrode disposed in each of the unit light emittingregions, the second electrode of which at least one region is providedopposite to the first electrode; and one or more LEDs provided in eachof the unit light emitting regions, the one or more LEDs beingelectrically connected between the first electrode and the secondelectrode.

The light emitting device may include a plurality of pixels provided inthe unit regions.

At least a surface of the dam may have hydrophilicity.

At least a surface of the barrier may have hydrophobicity.

A height of the dam may be equal to or greater than that of the barrier.

The dams disposed in the respective unit regions may have the sameheight.

The dam may be configured as a closed sidewall of which at least oneregion has a flat or curved surface.

The LEDs may be bar type LEDs, a length of each of the bar type LEDs maybe equal to or greater than a shortest distance between the firstelectrode and the second electrode, and one end and the other end of thebar type LEDs may be electrically in contact with the first electrodeand the second electrode, respectively.

The light emitting device may further include a filler provided in eachof the unit regions to fill in at least the dam, the filler including aplurality of scattering particles.

A plurality of dams spaced apart from one another may be provided ineach of the unit regions.

According to an aspect of the present disclosure, there is provided amethod of fabricating a light emitting device, the method including:preparing a base substrate, the base substrate including unit regionsand unit light emitting regions; forming a first electrode and a secondelectrode in each of the unit light emitting regions; forming a damsurrounding each of the unit light emitting regions and a barriersurrounding the dam, the barrier being spaced a predetermined distanceapart from the dam; and coating an LED solution in which LEDs aredispersed in the each of the unit regions to fill in at least the unitlight emitting regions. The LEDs may be bar type LEDs.

In the coating in the coating of the LED solution, the LED solution ofwhich amount is equal to or greater than a capacity of the dam may becoated in each of the unit regions.

In the coating of the LED solution, the LED solution of which amount isequal to or less than a total accommodation amount by the dam and thebarrier may be coated in each of the unit regions.

The forming of the dam may include: forming a base pattern of the dam bycoating and patterning at least one of one or more inorganic layers andone or more organic layers on the base substrate; and performinghydrophilic processing on a surface of the base pattern.

The forming of the base pattern may include forming at least oneinorganic layer on the base substrate using a sputtering process.

The forming of the barrier may include: forming a base pattern of thebarrier by coating and patterning at least one of one or more inorganiclayers and one or more organic layers on the base substrate; andperforming hydrophobic processing on a surface of the base pattern.

The forming of the dam and the forming of the barrier may besequentially performed.

The method may further include inducing an electric field between thefirst electrode and the second electrode while the coating the LEDsolution or after the coating the LED solution.

The method may further include removing a solvent of the LED solution.

The method may further include coating a filler including a plurality ofscattering particles in each of the unit regions.

In the coating of the filler, the filler of which amount is equal to orgreater than the capacity of at least the dam may be coated in each ofthe unit regions.

According to an aspect of the present disclosure, there is provided alight emitting display device including: a base substrate; a pixelregion provided on the base substrate; a barrier surrounding the pixelregion; a dam disposed in the pixel region to be spaced apart from thebarrier; a first electrode provided in a unit light emitting regionsurrounded by the dam; a second electrode provided in the unit lightemitting region, the second electrode of which at least one region isopposite to the first electrode; and one or more LEDs disposed in theunit light emitting region, the one or more LEDs being electricallyconnected between the first electrode and the second electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the example embodiments to those skilled in the art.

In the drawing figures, dimensions may be exaggerated for clarity ofillustration. It will be understood that when an element is referred toas being “between” two elements, it can be the only element between thetwo elements, or one or more intervening elements may also be present.Like reference numerals refer to like elements throughout.

FIG. 1 is a perspective view illustrating a bar type LED according to anembodiment of the present disclosure.

FIG. 2 is a structural diagram illustrating a light emitting deviceaccording to an embodiment of the present disclosure.

FIGS. 3A, 3B, 3C, 3D and 3E are circuit diagrams illustrating a unitregion of a light emitting device according to an embodiment of thepresent disclosure, which illustrate examples of a pixel constituting apassive light emitting display panel.

FIGS. 4A, 4B and 4C are circuit diagrams illustrating a unit region of alight emitting device according to an embodiment of the presentdisclosure, which illustrates examples of a pixel constituting an activelight emitting display panel.

FIG. 5 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region.

FIG. 6 is a sectional view taken along line I-I′ of FIG. 5.

FIG. 7 is a sectional view illustrating one region (A1 region) of FIG.6.

FIG. 8 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region.

FIG. 9 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region.

FIG. 10 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region.

FIGS. 11A, 11B, 11C, 11D, 11E, 11F and 11G are sectional viewssequentially illustrating a fabricating method of a light emittingdevice according to an embodiment of the present disclosure.

FIGS. 12A and 12B are sectional views illustrating a coating amount of abar type LED solution coated in an individual pixel region according toan embodiment of the present disclosure.

FIGS. 13A and 13B are plan views illustrating a luminance uniformityeffect according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.However, the present disclosure is not limited to the embodiments butmay be implemented into different forms. These embodiments are providedonly for illustrative purposes and for full understanding of the scopeof the present disclosure by those skilled in the art. In the entirespecification, when an element is referred to as being “connected” or“coupled” to another element, it can be directly connected or coupled tothe another element or be indirectly connected or coupled to the anotherelement with one or more intervening elements interposed therebetween.

Meanwhile, in the following embodiments and the attached drawings,elements not directly related to the present disclosure are omitted fromdepiction, and dimensional relationships among individual elements inthe attached drawings are illustrated only for ease of understanding butnot to limit the actual scale. It should note that in giving referencenumerals to elements of each drawing, like reference numerals refer tolike elements even though like elements are shown in different drawings.

According to an embodiment of the present disclosure, a light emittingdevice is not limited to the embodiments disclosed herein but may beimplemented into different forms using different light emitting sourcessuch as bar type LEDs and flip chip LEDs. Disclosed herein is anembodiment in which a bar type LED LD is used as a light emittingsource. A bar type LED LD will be first described, and a light emittingdevice to which the bar type LED LD is applied will be then described.

FIG. 1 is a perspective view illustrating a bar type LED LD according toan embodiment of the present disclosure. According to the embodiment ofthe present disclosure, a cylindrical bar type LED LD has beenillustrated in FIG. 1, but the present disclosure is not limitedthereto.

Referring to FIG. 1, the bar type LED LD according to the embodiment ofthe present disclosure includes first and second conductivesemiconductor layers 11 and 13 and an active layer 12 interposed betweenthe first and second conductive semiconductor layers 11 and 13. Forexample, the bar type LED LD may be implemented as a stack structure inwhich the first conductive semiconductor layer 11, the active layer 12,and the second conductive semiconductor layer 13 are sequentiallystacked. In some embodiments, the bar type LED LD may further include aninsulating film 14. In addition, the bar type LED LD may further includea first electrode (not shown) and a second electrode (not shown).

According to the embodiment of the present disclosure, the bar type LEDLD extends along one direction. If it is assumed that the extendingdirection of the bar type LED LD is a length direction, the bar type LEDLD has a first end portion and a second end portion. In an embodiment ofthe present disclosure, one of the first and second conductivesemiconductor layers 11 and 13 is disposed at the first end portion, andthe other of the first and second conductive semiconductor layers 11 and13 is disposed at the second end portion.

In some embodiments, the bar type LED LD may be provided in acylindrical shape as shown in FIG. 1, but the shape of the bar type LEDLD is not limited thereto. Here, the term “bar type” includes a rod-likeshape or bar-like shape, which is long in its length direction (i.e.,its aspect ratio is greater than 1), such as a cylindrical column or apolygonal column. For example, the bar type LED LD may have a lengthgreater than a diameter thereof.

The bar type LED LD may be fabricated small enough to have a diameterand/or a length, for example, to a degree of micro or nano scale.However, the size of the bar type LED LD according to the embodiment ofthe present disclosure is not limited thereto. For example, the size ofthe bar type LED LD may be changed to correspond to required conditionsof a light emitting device to which the bar type LED LD is applied.

The first conductive semiconductor layer 11 may include, for example, atleast one n-type semiconductor layer. For example, the first conductivesemiconductor layer 11 may include at least one semiconductor materialselected from InAlGaN, GaN, AlGaN, InGaN, AlN, and InN, and may includea semiconductor layer doped with a first conductive dopant such as Si,Ge, or Sn. The material constituting the first conductive semiconductorlayer 11 is not limited thereto, and various materials may be includedin the first conductive semiconductor layer 11.

The active layer 12 is formed on the first conductive semiconductorlayer 11, and may be formed in a single or multiple quantum wellstructure. In some embodiments, a clad layer (not shown) doped with aconductive dopant may be formed over and/or under the active layer 12.For example, the clad layer may be implemented as an AlGaN layer orInAlGaN layer. In addition, it will be apparent that a material such asAlGaN or AlInGaN may also be used for the active layer 12. If anelectric field having a predetermined voltage or more is applied to bothends of the bar type LED, the bar type LED emits light as electron-holepairs are combined in the active layer 12.

The second conductive semiconductor layer 13 is formed on the activelayer 12, and may include a semiconductor layer having a different typefrom the first conductive semiconductor layer 11. For example, thesecond conductive semiconductor layer 13 may include at least on p-typesemiconductor layer. For example, the second conductive semiconductorlayer 13 may include at least one semiconductor material selected fromInAlGaN, GaN, AlGaN, InGaN, AlN, and InN, and may include asemiconductor layer doped with a second conductive dopant such as Mg.The material constituting the second conductive semiconductor layer 13is not limited thereto, and various materials may be included in thesecond conductive semiconductor layer 13.

Meanwhile, in some embodiments, in addition to the first conductivesemiconductor layer 11, the active layer 12, and the second conductivesemiconductor layer 13, which are described above, the bar type LED LDmay further include a phosphor layer, an active layer, a semiconductorlayer, and/or an electrode layer, which are formed over and/or undereach of the first conductive semiconductor layer 11, the active layer12, and/or the second conductive semiconductor layer 13. For example,the bar type LED LD may further include a first electrode (not shown)and a second electrode (not shown). The first electrode may beelectrically connected to the first conductive semiconductor layer 11,and the second electrode may be electrically connected to the secondconductive semiconductor layer 13. For example, the first electrode maybe electrically connected to the bar type LED LD through one surface ofthe first conductive semiconductor layer 11 (e.g., a lower surface ofthe bar type LED LD, which is not covered by the insulating film 14 inFIG. 1), and the second electrode may be electrically connected to thebar type LED LD through one surface of the second conductivesemiconductor layer 13 (e.g., an upper surface of the bar type LED LD,which is not covered by the insulating film 14 in FIG. 1). In someembodiments, a conductive contact layer (not shown) may be furtherprovided between the first electrode and the first conductivesemiconductor layer 11 and/or between the second electrode and thesecond conductive semiconductor layer 13.

In some embodiments, the bar type LED LD may further include theinsulating film 14, but the present disclosure is not limited thereto.That is, the insulating film 14 may be omitted.

In some embodiments, the insulating film 14 may be provided to cover atleast one region of the first conductive semiconductor layer 11, theactive layer 12, and the second conductive semiconductor layer 13. Forexample, the insulating film 14 may be provided to expose at leastportions of both the end portions of the bar type LED LD. FIG. 1 is astate in which a portion of the insulating film 14 is removed forconvenience of description. In FIG. 1, it has been illustrated that, asa side portion of the insulating film 14 is removed, portions of thefirst conductive semiconductor layer 11, the active layer 12, and thesecond conductive semiconductor layer 13 are exposed. However, in theactual bar type LED LD, the entire side surface of the cylindricalcolumn may be surrounded by the insulating film 14. In otherembodiments, the insulating film 14 may expose at least one side regionof the first conductive semiconductor layer 11 and/or the secondconductive semiconductor layer 13.

The insulating film 14 is formed to surround at least one portion ofouter circumferential surfaces of the first conductive semiconductorlayer 11, the active layer 12, and/or the second conductivesemiconductor layer 13. For example, the insulating film 14 may beformed to at least surround the outer circumferential surface of theactive layer 12. In some embodiments, the insulating film 14 may beformed of a transparent insulating material. For example, the insulatingfilm 14 may include at least one selected from the group consisting ofSiO₂, Si₃N₄, Al₂O₃, and TiO₂, but the present disclosure is not limitedthereto. That is, various materials having insulating properties may beused.

In a non-restrictive embodiment, the insulating film 14 may be made of ahydrophobic material, or a hydrophobic film made of a hydrophobicmaterial may be further provided on the insulating film 14. In someembodiments, the hydrophobic material may be a material containingfluorine to exhibit hydrophobicity. In some embodiments, the hydrophobicmaterial may be applied in the form of a self-assembled monolayer (SAM)to the bar type LED LD. In this case, the hydrophobic material mayinclude octadecyltrichlorosilane, fluoroalkyltrichlorosilane,perfluoroalkyltriethoxysilane, and the like. In addition, thehydrophobic material may be a commercialized fluorine-containingmaterial such as Teflon™ or Cytop™, or a material corresponding thereto.

If the insulating film 14 is formed, the active layer 12 can beprevented from being short-circuited with the first electrode (notshown) and/or the second electrode (not shown). Further, as theinsulating film 14 is formed, a surface defect of the bar type LED LDcan be minimized, thereby improving lifespan and luminous efficiency.Furthermore, when a plurality of bar type LEDs LD are densely arranged,the insulating film 14 can prevent an undesired short circuit that mayoccur between the bar type LEDs LD.

Additionally, if the insulating film 14 is made of a hydrophobicmaterial or if a hydrophobic film is provided on the insulating film 14,when an LED solution containing bar type LEDs LD is coated (or dropped),the bar type LEDs LD may be relatively uniformly distributed in the LEDsolution. Thus, the bar type LEDs LD can be uniformly coated ordistributed in each of unit regions constituting the light emittingdevice.

The above-described bar type LED LD may be used as a light emittingsource for various light emitting devices. For example, the bar type LEDLD may be used as a light emitting source for lighting devices orself-luminescent display panels.

FIG. 2 is a structural diagram illustrating a light emitting deviceaccording to an embodiment of the present disclosure. In someembodiments, in FIG. 2, a light emitting display device has beenillustrated as an example of light emitting devices using bar type LEDsLD, but the light emitting device according to the present disclosure isnot limited to the light emitting display device. For example, the lightemitting device according to the present disclosure may be a differenttype of light emitting device such as a lighting device.

Referring to FIG. 2, the light emitting device according to theembodiment of the present disclosure includes a timing controller 110, ascan driver 120, a data driver 130, and a light emitting unit 140. Whenthe light emitting device is a light emitting display device like thisembodiment, the light emitting unit 140 may mean the entire pixel regionimplemented on a display panel.

The timing controller 110 receives various control signals and imagedata, which are required to drive the light emitting unit 140, from anoutside (e.g., a system for transmitting image data). The timingcontroller 110 realigns the received image data and transmits therealigned image data to the data driver 130. Also, the timing controller110 generates scan control signals and data control signals, which arerequired to drive the respective scan and data drivers 120 and 130, andtransmits the generated scan and data control signals to the respectivescan and data drivers 120 and 130.

The scan driver 120 receives a scan control signal supplied from thetiming controller 110, and generates a scan signal corresponding to thescan control signal. The scan signal generated by the scan driver 120 issupplied to unit regions (e.g., pixels) 142 through scan lines S1 to Sn.

The data driver 130 receives a data control signal and the realignedimage data, supplied from the timing controller 110, and generates adata signal corresponding to the data control signal and the realignedimage data. The data signal generated by the data driver 130 is outputto data lines D1 to Dm. The data signal output to the data lines D1 toDm is input to unit regions 142 on a horizontal pixel line selected bythe scan signal.

The light emitting unit 140 may include a plurality of pixels 142connected to the scan lines S1 to Sn and the data lines D1 to Dm. Insome embodiments, each of the pixels 142 may include one or more bartype LEDs LD as shown in FIG. 1. The pixels 142 selectively emit light,corresponding to a data signal input from the data lines D1 to Dm when ascan signal is supplied from the scan lines S1 to Sn. For example, eachof the pixels 142 may emit light with a luminance corresponding to theinput data signal during each frame period. A pixel 142 receiving a datasignal corresponding to a black luminance does not emit light during acorresponding frame period, thereby displaying black. When the lightemitting unit 140 is a pixel unit (display area) of an active lightemitting display panel, the light emitting unit 140 may be driven bybeing further supplied with first and second pixel power sources as wellas the scan and data signals.

FIGS. 3A to 3E are circuit diagrams illustrating a unit region of alight emitting device according to an embodiment of the presentdisclosure, which illustrate examples of a pixel constituting a passivelight emitting display panel. For convenience, a jth (j is a naturalnumber) pixel on an ith (i is a natural number) horizontal pixel line isillustrated in FIGS. 3A to 3E. As a non-restrictive example related tothe pixel shown in FIGS. 3A to 3E, the pixel may be one of red, green,blue, and white pixels.

Referring to FIG. 3A, the pixel 142 includes a bar type LED LD connectedbetween a scan line Si and a data line Dj. In some embodiments, a firstelectrode (e.g., an anode electrode) of the bar type LED LD may beconnected to the scan line Si, and a second electrode (e.g., a cathodeelectrode) of the bar type LED LD may be connected to the data line Dj.When a voltage equal to or greater than a threshold voltage is appliedbetween the first electrode and the second electrode, the bar type LEDLD emits light with a luminance corresponding to the magnitude of theapplied voltage. That is, the voltage of a scan signal applied to thescan line Si and/or a data signal applied to the data line Dj isadjusted, thereby controlling the light emission of the pixel 142.

Referring to FIG. 3B, in some embodiments, the pixel 142 may include twoor more bar type LEDs LD connected in parallel. In this case, theluminance of the pixel 142 may correspond to the sum of brightnesses ofa plurality of LEDs LD constituting the pixel 142. If the pixel 142includes a plurality of bar type LEDs LD, particularly, a large numberof bar type LEDs LD, although a defect occurs in some bar type LEDs LD,the remaining bar type LEDs LD may emit light, thus, defect can beprevented from causing a defect of the pixel 142 itself.

Referring to FIG. 3C, in some embodiments, the connecting direction ofthe bar type LEDs LD provided in the pixel 142 may be altered. Forexample, the first electrode (anode electrode) of the bar type LED LDmay be connected to the data line Dj, and the second electrode (cathodeelectrode) of the bar type LED nLED may be connected to the scan lineSi. The direction of a voltage applied between the scan line Si and thedata line Dj in the embodiment of FIG. 3A and the direction of a voltageapplied between the scan line Si and the data line Dj in the embodimentof FIG. 3C may be opposite to each other.

Referring to FIG. 3D, the pixel 142 according the embodiment of FIG. 3Cmay also include two or more bar type LEDs LD connected in parallel.

Referring to FIG. 3E, in some embodiments, the pixel 142 may include aplurality of bar type LEDs LD connected in different directions. Forexample, the pixel 142 may include one or more bar type LEDs LD eachhaving the first electrode (anode electrode) connected to the scan lineSi and the second electrode (cathode electrode) connected to the dataline Dj, and one or more bar type LEDs LD each having the firstelectrode (anode electrode) connected to the data line Dj and the secondelectrode (cathode electrode) connected to the san line Si.

In some embodiments, the pixel 142 of FIG. 3E may be DC driven or ACdriven. When the pixel 142 of FIG. 3E is DC driven, forward connectedbar type LEDs LD may emit light, and reverse connected LEDs LD may notemit light. Meanwhile, when the pixel 142 of FIG. 3E is AC driven,forward connected bar type LEDs LD may emit light according to thedirection of an applied voltage. That is, when the pixel 142 of FIG. 3Eis AC driven, the bar type LEDs LD included in the pixel 142 mayalternately emit light according to the direction of the appliedvoltage.

FIGS. 4A to 4C are circuit diagrams illustrating a unit region of alight emitting device according to an embodiment of the presentdisclosure, which illustrates examples of a pixel constituting an activelight emitting display panel. In FIGS. 4A to 4C, components similar oridentical to those of FIGS. 3A to 3E are designated by like referencenumerals, and their detailed descriptions will be omitted.

Referring to FIG. 4A, the pixel 142 includes one or more bar type LEDsLD and a pixel circuit 144 connected thereto.

A first electrode (e.g., an anode electrode) of the bar type LED LD isconnected to a first pixel power source ELVDD via the pixel circuit 144,and a second electrode (e.g., a cathode electrode) of the bar type LEDLD is connected to a second pixel power source ELVSS. The first pixelpower source ELVDD and the second pixel power source ELVSS may havepotentials different from each other. For example, the second pixelpower source ELVSS may have a potential lower by a threshold voltage ormore of the bar type LED LD than that of the first pixel power sourceELVDD. Each of the bar type LEDs LD emits light with a luminancecorresponding to a driving current controlled by the pixel circuit 144.

Meanwhile, although an embodiment in which only one bar type LED LD isincluded in the pixel 142 has been disclosed in FIG. 4A, the presentdisclosure is not limited thereto. For example, the pixel 142 mayinclude a plurality of bar type LEDs LD connected in parallel.

In some embodiments, the pixel circuit 144 may include first and secondtransistors M1 and M2 and a storage capacitor Cst. However, thestructure of the pixel circuit 144 is not limited to the embodimentshown in FIG. 4A.

A first electrode of the first transistor (switching transistor) M1 isconnected to a data line Dj, and a second electrode of the firsttransistor M1 is connected to a first node N1. Here, the first andsecond electrodes of the first transistor M1 are electrodes differentfrom each other. For example, if the first electrode is a sourceelectrode, the second electrode may be a drain electrode. In addition, agate electrode of the first transistor M1 is connected to a scan lineSi. The first transistor M1 is turned on when a scan signal having avoltage (e.g., a gate-on voltage of a low level) at which the firsttransistor M1 can be turned on is supplied from the scan line Si, toallow the data line Dj and the first node N1 to be electricallyconnected to each other. At this time, a data signal of a correspondingframe is supplied to the data line Dj. Accordingly, the data signal istransmitted to the first node N1. The data signal transmitted to thefirst node N1 is charged in the storage capacitor Cst.

A first electrode of the second transistor (driving transistor) M2 isconnected to the first pixel power source ELVDD, and a second electrodeof the second transistor M2 is connected to the first electrode of thebar type LED LD. In addition, a gate electrode of the second transistorM2 is connected to the first node N1. The second transistor M2 controlsthe amount of driving current supplied to the bar type LED LD,corresponding to a voltage of the first node N1.

One electrode of the storage capacitor Cst is connected to the firstpixel power source ELVDD, and the other electrode of the storagecapacitor Cst is connected to the first node N1. The storage capacitorCst charges a voltage corresponding to the data signal supplied to thefirst node N1, and maintains the charged voltage until a data signal ofa next frame is supplied.

For convenience, the pixel circuit 144 having a relatively simplestructure including the first transistor M1 for transmitting a datasignal to the inside of the pixel 142, the storage capacitor Cst forstoring the data signal, and the second transistor M2 for supplying, tothe bar type LED LD, a driving current corresponding to the data signalhas been illustrated in FIG. 4A. However, the present disclosure is notlimited thereto, and the structure of the pixel circuit 144 may bevariously modified and implemented. For example, it will be apparentthat the pixel circuit 144 may further include other circuit elementssuch as at least one transistor for compensating for a threshold voltageof the second transistor M2, at least one transistor for initializing avoltage of the first node N1 or a voltage applied to one electrode ofthe bar type LED LD, and/or at least one transistor for controlling alight emission time, or a boosting capacitor for boosting the voltage ofthe first node N1.

In FIG. 4A, all of the transistors, e.g., both of the first and secondtransistors M1 and M2, which are included in the pixel circuit 144, areillustrated as p-type transistors, but the present disclosure is notlimited thereto. That is, at least one of the transistors M1 and M2included in the pixel circuit 144 may be replaced with an n-typetransistor.

Referring to FIG. 4B, in some embodiments, the first and secondtransistors M1 and M2 may be implemented as n-type transistors. Theconfiguration or operation of the pixel circuit 144 shown in FIG. 4B issimilar to that of the pixel circuit 144 of FIG. 4A, except that theconnecting positions of some components are changed due to a change intransistor type. Therefore, detailed description of the pixel circuit144 of FIG. 4B will be omitted.

Referring to FIG. 4C, in some embodiments, the pixel 142 may include aplurality of bar type LEDs LD connected in different directions. In thiscase, the pixel 142 may be DC driven or AC driven. This has already beendescribed in FIG. 3E, and therefore, its detailed description will beomitted.

FIG. 5 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region EPA. FIG. 6 is a sectional viewtaken along line I-I′ of FIG. 5. FIG. 7 is a sectional view illustratingone region (A1 region) of FIG. 6. FIG. 8 is a plan view illustrating aunit region of a light emitting device according to an embodiment of thepresent disclosure, which illustrates an individual pixel region EPA.FIG. 8 illustrates a modification of FIG. 5.

For convenience, in FIGS. 5 to 8, a scan line Si and a data line Dj arearranged at the outside of the individual pixel region EPA, but thepresent disclosure is not limited thereto. For example, at least oneregion of the scan line Si and/or the data line Dj may overlap with abarrier 240 that defines each pixel region EPA, or may be disposedinside each pixel region EPA.

Referring to FIG. 5, the unit region according to the embodiment of thepresent disclosure may be, for example, an individual pixel region EPAin which each of the pixels 142 constituting the light emitting unit 140shown in FIG. 2 is provided. That is, the light emitting deviceaccording to the embodiment of the present disclosure may be a lightemitting display device including a plurality of individual pixelregions EPA shown in FIG. 5 and the pixel 142 shown in FIGS. 2 to 4C maybe provided in each pixel region EPA. However, the present disclosure isnot limited thereto, and it will be apparent that the present disclosuremay be applied to other light emitting devices as well as the lightemitting display device.

In some embodiments, each pixel region EPA may be disposed in a regiondefined by a corresponding scan line Si and a scan line adjacent to thecorresponding scan line Si and a corresponding data line Dj and a dataline adjacent to the corresponding data line Dj. One or more unit lightemitting regions EA may be defined in the pixel region EPA, and aperipheral region PA may be defined at the periphery of the unit lightemitting region EA. That is, in some embodiments, the unit lightemitting region EA may be an effective light emitting region of theindividual pixel region EPA, and the peripheral region PA may be theremaining region of the individual pixel region EPA which surrounds theunit light emitting region EA.

One or more first electrodes 210 and one or more second electrodes 220are provided in each pixel region EPA. In some embodiments, the firstelectrode 210 and the second electrode 220 may be disposed to form apair such that at least one region of the first electrode 210 and atleast one region of the second electrode 220 are opposite to each other,particularly in the unit light emitting region EA.

In some embodiments, the first electrode 210 and the second electrode220, as shown in FIGS. 6 and 7, may be disposed in the same layer on abase substrate 200 to be spaced apart from each other. For example, thefirst and second electrodes 210 and 220 may be alternately disposed tobe spaced apart from each other at the same height (or at the samelevel) with respect to an upper surface of the base substrate 200.However, the present disclosure is not necessarily limited thereto. Forexample, the first and second electrodes 210 and 220 may be disposed inlayers different from each other. The first electrode 210 and the secondelectrode 220 may be formed of the same material, for example, a datametal forming the data line Dj or a gate metal forming the scan line Si.

In some embodiments, one or more insulating layers 201 may be providedbetween the base substrate 200 and the first and second electrodes 210and 220. In some embodiments, the insulating layer 201 may be a bufferlayer that forms a planarized surface on the base substrate 200 andblocks an impurity element from penetrating through the base substrate200. The insulating layer may include an oxide layer or nitride layersuch as SiO_(x) or SiN_(x), but the present disclosure is not limitedthereto. Alternately, in other embodiments, the insulating layer 201 maybe omitted.

In an embodiment of the present disclosure, the shape of the firstelectrode 210 and the second electrode 220 is not particularly limited.That is, the first electrode 210 and the second electrode 220 may beimplemented in various shapes. For example, the first electrode 210 andthe second electrode 220, as shown in FIGS. 5 to 7, may have a structurein which the first electrode 210 and the second electrode 220 aredisposed to be spaced apart from each other on the same plane, and eachof the first electrode 210 and the second electrode 220 branches offinto a plurality of electrode lines in one region such that theelectrode lines of the first electrode 210 and the second electrode 220are alternately disposed. Alternatively, the first electrode 210 and thesecond electrode 220 may be respectively implemented in vortex shapesdisposed to be spaced apart at positions corresponding to each other.Alternatively, the first electrode 210 and the second electrode 220 maybe respectively implemented in polygonal shapes disposed in parallel toeach other to be spaced apart at a predetermined distance or more, e.g.,rectangular bar shapes parallel to each other, and the like.

In some embodiments, each of the first electrode 210 and the secondelectrode 220 may be electrically connected to any one of the scan lineSi and the data line Dj. For example, when the first electrode 210 andthe second electrode 220 are formed of the data metal forming the dataline Dj, the first electrode 210 may be electrically connected to thescan line Si through a contact hole, and the second electrode 220 may beintegrally formed with the data line Dj. For example, when the firstelectrode 210 and the second electrode 220 are formed of the gate metalforming the scan line Si, the first electrode 210 may be integrallyformed with the scan line Si and the second electrode 220 may beelectrically connected to the data line Dj through a contact hole. Forexample, when the first electrode 210 and the second electrode 220 areformed of a conductive material other than the gate metal and the datametal, the first electrode 210 and the second electrode 220 may beelectrically connected to the scan line Si and the data line Dj througha first contact hole and a second contact hole, respectively.

In some embodiments, the first electrode 210 and/or the second electrode220 may include at least one of a metal, an alloy thereof, a conductivepolymer, and a conductive metal oxide. Examples of a metal capable ofconstituting the first electrode 210 and/or the second electrode 220 maybe Ti, Cu, Mo, Al, Au, Cr, TiN, Ag, Pt, Pd, Ni, Sn, Co, Rh, Ir, Fe, Ru,Os, Mn, W, Nb, Ta, Bi, Sb, Pb, and the like. In addition, various metalsmay be used as the metal capable of constituting the first electrode 210and/or the second electrode 220. Examples of an alloy capable ofconstituting the first electrode 210 and/or the second electrode 220 maybe MoTi, AlNiLa, and the like. In addition, various alloys may be usedas the alloy capable of constituting the first electrode 210 and/or thesecond electrode 220. Examples of a multi-layered layer capable ofconstituting the first electrode 210 and/or the second electrode 220 maybe Ti/Cu, Ti/Au, Mo/Al/Mo, ITO/Ag/ITO, TiN/Ti/Al/Ti, TiN/Ti/Cu/Ti, andthe like. In addition, various conductive materials having multi-layeredstructures may be used as the multi-layered layer capable ofconstituting the first electrode 210 and/or the second electrode 220.Examples of a conductive polymer capable of constituting the firstelectrode 210 and/or the second electrode 220 may bepolythiophene-based, polypyrrole-based, polyaniline-based,polyacetylene-based, and polyphenylene-based compounds, mixturesthereof, and the like. Particularly, a PEDOT/PSS compound among thepolythiophene-based compounds may be used as the conductive polymercapable of constituting the first electrode 210 and/or the secondelectrode 220. Examples of a conductive metal oxide capable ofconstituting the first electrode 210 and/or the second electrode 220 maybe ITO, IZO, AZO, ITZO, ZnO, SnO₂, and the like. In addition, a materialcapable of providing conductivity as well as the above-describedconductive materials may be used as the material constituting the firstelectrode 210 and/or the second electrode 220. The electrode structureof the first electrode 210 and/or the second electrode 220 is notparticularly limited, and the first electrode 210 and/or the secondelectrode 220 may be variously formed in a single layer or multiplelayers.

One or more bar type LEDs LD may be electrically connected between thefirst and second electrodes 210 and 220. For example, a plurality of bartype LEDs LD may be electrically connected between the first and secondelectrodes 210 and 220. That is, in the light emitting device accordingto the embodiment of the present disclosure, at least one bar type LEDLD may be provided in each unit region, i.e., the individual pixelregion EPA. Particularly, one or more bar type LEDs LD (in anembodiment, a plurality of bar type LEDs LD) electrically connectedbetween the first and second electrodes 210 and 220 may be provided inthe unit light emitting region EA of each pixel region EPA.

In some embodiments, the at least one bar type LED LD provided in eachunit light emitting region EA may be electrically connected between thefirst and second electrodes 210 and 220 in a form in which one end ofthe bar type LED LD is physically and/or electrically in contact withthe first electrode 210 and the other end of the bar type LED LD isphysically and/or electrically in contact with the second electrode 220.In this case, as shown in FIG. 7, a length L of the bar type LED LD maybe equal to or greater than a shortest distance D between the first andsecond electrodes 210 and 220 adjacent to each other.

In some embodiments, a conductive contact layer 250 may be additionallyprovided at both ends of the bar type LED LD. In this case, even whenthe side surface of the bar type LED LD is covered by the insulatingfilm 14 as shown in FIG. 1, both ends of the bar type LED LD, which arenot covered by the insulating film 14, may electrically connected to therespective first and second electrodes 210 and 220 by the conductivecontact layer 250. In addition, when the conductive contact layer 250 isprovided, the bar type LED LD can be prevented from being separated fromits aligned position.

In an embodiment of the present disclosure, the number or scatteringform of bar type LEDs LD connected between the first and secondelectrodes 210 and 220 is not particularly limited. In addition,although not shown in the drawings, at least one bar type LED that isnot completely connected to the first and second electrodes 210 and 220but randomly disposed between the first and second electrodes 210 and220 may be further provided in each pixel region EPA. That is, at leastone bar type LED LD that is not aligned but randomly disposed betweenthe first and second electrodes 210 and 220 may be further provided inthe unit light emitting region EA and/or the peripheral region PA.

In addition, for convenience, it has been illustrated in FIGS. 5 to 8that the bar type LEDs LD connected between the first and secondelectrodes 210 and 220 are uniformly aligned in a specific direction(e.g., a direction in parallel to the data line Dj), but the alignmentof the bar type LEDs LD is not limited thereto. For example, at leastsome of the bar type LEDs LD may be aligned in an oblique direction orthe like between the first and second electrodes 210 and 220. That is,the connection direction and/or alignment direction, and the like of thebar type LEDs LD are not particularly limited.

In addition, the embodiments shown in FIGS. 5 to 8, for example,correspond to the pixel 142 having the structure shown in FIG. 3B, etc.When the structure of the pixel 142 is changed, the connection structureof the first electrode 210 and/or the second electrode 220 may bechanged. For example, in some embodiments, the pixel circuit 144 shownin FIGS. 4A to 4C, etc. may be further provided in each pixel regionEPA.

In some embodiments, the pixel circuit 144 may be provided, togetherwith the first and second electrodes 210 and 220, on the same surface ofthe base substrate 200. In this case, the pixel circuit 144 may bedisposed in the a same layer as the first and second electrodes 210 and220, or may be disposed in a different layer from the first and secondelectrodes 210 and 220. For example, the pixel circuit 144 may bedisposed in an intermediate layer (not shown) interposed between theinsulating layer 201 and a predetermined layer in which the first andsecond electrodes 210 and 220 are disposed, to be electrically connectedto the first electrode 210 and/or the second electrode 220 through acontact hole, a via hole, etc. In this case, the first electrode 210and/or the second electrode 220 may be electrically connected to thepixel circuit 144 or the first or second pixel power source ELVDD orELVSS, shown in FIGS. 4A to 4C, etc., instead of being connected to thescan line Si or the data line Dj.

In the light emitting device to which the bar type LEDs LD are applied,when assuming that the magnitudes of voltages between the first andsecond electrodes 210 and 220 in the respective pixel areas EPA aresubstantially equal to each other, the luminance of the individual pixelarea EPA may be changed depending on the number of bar type LEDs LDelectrically connected between the first and second electrodes 210 and220, i.e., the number of effective bar type LEDs LD provided in the unitlight emitting region EA of each pixel region EPA. Particularly, when avariation in number of effective bar type LEDs LD included in unit lightemitting regions EA of pixel regions EPA is severe, the light emittingdevice may exhibit entirely non-uniform luminance characteristics.

Thus, in an embodiment of the present disclosure, there are provided alight emitting device and a fabricating method thereof, which can reducea variation in luminance between pixel regions EPA and simultaneouslyimprove visibility. Specifically, in the embodiment of the presentdisclosure, a dam 230 spaced apart from the barrier 240 to surround apredetermined unit light emitting region EA is formed in the individualpixel region EPA surrounded by the barrier 240. According to theembodiment of the present disclosure, it is possible to provide a lightemitting device and a fabricating method thereof, in which amounts of anLED solution coated (or distributed) in the respective unit lightemitting regions EA are controlled, thereby achieving uniform luminancecharacteristics and visibility.

More specifically, in an embodiment of the present disclosure, each unitlight emitting region EA may be surrounded by the dam 230. In addition,a unit region including at least one unit light emitting region EA,i.e., each pixel region EPA may be surrounded by the barrier 240. Thatis, when viewed on a plane, an area of a region embraced by the dam 230(i.e., a sectional area of the dam 230) may be smaller than an area of aregion embraced by the barrier 240 (i.e., a sectional area of thebarrier 240). That is, the dam 230 is disposed inside the barrier 240,and lateral and longitudinal lengths of the dam 230 may be smaller thanthose of the barrier 240.

Specifically, the dam 230 may be disposed to be spaced apart from thebarrier 240 in each pixel region EPA at a predetermined distance. Thedam 230 may be disposed at a boundary of unit light emitting regions EAeach including one or more first and second electrodes 210 and 220 andone or more bar type LEDs LD. In some embodiments, an upper portion ofthe dam 230 is opened. For example, the dam 230 may be configured with aclosed type sidewall of which at least one region has a flat or curvedsurface.

That is, the dam 230, as shown in FIG. 6, may be a three-dimensionalstructure having a predetermined height H1. A capacity of the dam 230may be determined by the height H1 of the dam 230 along with thesectional area of the dam 230 (i.e., the area of the unit light emittingregion EA). Thus, the capacity of the dam 230 can be easily controlledby adjusting the area and/or height (H1) of the dam 230.

In some embodiments, the height H1 of the dam 230 may be equal to orgreater than a height H2 of the barrier 240. For example, the height H1of the dam 230 may be greater than the height H2 of the barrier 240. Inthis case, in a process of coating (or dropping), an LED solution inwhich a plurality of bar type LEDs LD are scattered in the LED solution,even when an excessive amount of the LED solution is coated (or dropped)in the pixel region EPA due to a variation in coating amount of acoating (or dropping) equipment, the excessive amount of the LEDsolution is overflown to a space between the dam 230 and the barrier240.

However, in the present disclosure, it is not limited that the height H1of the dam 230 is equal to or greater than the height H2 of the barrier240. For example, if a total accommodation amount of each pixel regionEPA by the dam 230 and the barrier 240 is large enough to accommodate aone-time coating (or dropping) amount or more of the LED solution, theheight H1 of the dam 230 may be equal to or less than the height H2 ofthe barrier 240.

In some embodiments, when viewed on a plane, the dam 230 may have aclosed type quadrangular shape as shown in FIG. 5. However, the shape ofthe dam 230 is not limited thereto, and may be variously modified.

For example, when viewed on a plane, the dam 230 may be implemented in aclosed type polygonal shape. Alternatively, the dam 230 may be providedin various shapes such as a circle or an ellipse including curved sides,and a semicircle, a semi-ellipse, etc., including linear and curvedsides. In some embodiments, when the dam 230 has linear sides, at leastsome of corners of each of the shapes may be formed in a curve. Forexample, as shown in FIG. 8, the dam 230 basically has a quadrangularshape, and at least some of corner portions at which adjacent linearsides meet each other may be rounded in a curved shape. That is, whenviewed on a plane, the dam 230 may have a shape such as a closed typepolygonal shape, a circular shape, or an elliptical shape, or may havevarious closed type shapes including a shape including linear and curvedsides.

In some embodiments, the dam 230 may include one or more organic layersmade of a photo resist (hereinafter, abbreviated as “PR”) based organicmaterial, etc. and/or one or more inorganic layers made of an inorganicmaterial such as SiN_(x) or SiO_(x). For example, the dam 230 isconfigured in a multi-layered structure to include one or more organiclayers and one or more inorganic layers, so that the height H1 of thedam 230 can be easily controlled.

Meanwhile, in some embodiments, when the dam 230 includes at least oneinorganic layer, the dam 230 is fabricated using a sputtering process,so that the height H1 of the dam 230 can be precisely adjusted, forexample, in the unit of nanometers (nm). Thus, the capacity of the dam230 provided in each pixel region EPA can be easily controlled.

In some embodiments, at least a surface of the dam 230 may havehydrophilicity. For example, the dam 230 may be made of a hydrophilicmaterial, or the surface of the dam 230 may include a hydrophilic film.In some embodiments, the hydrophilic material capable of constitutingthe dam 230 may be an inorganic insulating material such as SiN_(x) orSiO_(x), but the present disclosure is not limited thereto. For example,the hydrophilic material capable of constituting the dam 230 may be anorganic insulating material. In addition, the dam 230 may be treated tohave hydrophilicity using plasma, etc.

When the dam 230 has the hydrophilicity, if an LED solution of whichamount is equal to or greater than the capacity of the dam 230 is coated(or dropped) in at least the unit light emitting region EA in the dam230, the LED solution may easily overflow over the dam 230. That is, ifthe dam 230 has the hydrophilicity, a surface flatness of the LEDsolution accommodated in the dam 230 when the LED solution is fullyfilled in the dam 230 is maintained high.

By forming the hydrophilic dam 230 as described above, when an LEDsolution is coated in the unit light emitting region EA through aninkjet apparatus, a nozzle apparatus, or the like, it is possible toprevent a phenomenon that the LED solution piles up on the unit lightemitting region EA. Thus, although a variation in coating or droppingamount of the LED solution occurs due to a variation in coatingequipment, etc., only the LED solution of a certain amount can beaccommodated in the dam 230.

In some embodiments, the barrier 240 may be disposed at a boundary ofpixel regions EPA to surround each individual pixel region EPA. Thebarrier 240 may be spaced a predetermined distance apart from the dam230. That is, each pixel region EPA may be defined by the barrier 240,and the barrier 240 may be a pixel defining layer PDL. The barrier 240may serve as a bank structure when an LED solution is coated.

In some embodiments, when viewed on a plane, the barrier 240 may have aclosed shape as shown in FIGS. 5 to 8. The barrier 240 may have anapproximately quadrangular shape, but the present disclosure is notlimited thereto. That is, like the shape of the dam 230, the shape ofthe barrier 240 may be variously modified.

In addition, the barrier 240, as shown in FIG. 6, may be a side closedtype three-dimensional structure having a predetermined height H2. Theheight H2 of the barrier 240 may be equal to or different from theheight H1 of the dam 230. For example, as described above, the height H2of the barrier 240 may be equal to or less than the height H1 of the dam230 with respect to one surface (e.g., the upper surface) of the basesubstrate 200.

In some embodiments, at least a surface of the barrier may havehydrophobicity. For example, the barrier 240 may be made of ahydrophobic material, or the surface of the barrier 240 may include ahydrophobic film. In some embodiments, the hydrophobic material capableof constituting the barrier 240 may be a material containing fluorine,but the present disclosure is not limited thereto. For example, thehydrophobic material may be a polymer material having hydrophobicproperties, e.g., a material obtained by mixing any one or two or moreof polyimide, styrene, methylmathacrylate, and polytetrafluoroethylene,which contain fluorine. In some embodiments, the hydrophobic materialmay be a material containing fluorine to exhibit hydrophobicity. In someembodiments, the hydrophobic material may be applied in the form of aself-assembled monolayer (SAM) to the bar type LED LD. In this case, thehydrophobic material may include octadecyltrichlorosilane,fluoroalkyltrichlorosilane, perfluoroalkyltriethoxysilane, and the like.In addition, the hydrophobic material may be a commercializedfluorine-containing material such as Teflon™ or Cytop™, or a materialcorresponding thereto.

If the barrier 240 has the hydrophobicity, although an excessive amountof the LED solution is coated in the pixel region EPA due to a variationin coating equipment, etc. when the LED solution is coated in the pixelregion EPA, the hydrophobic barrier 240 may prevent the excessive amountof the LED solution from being introduced into adjacent pixel regionsEPA, etc.

As described above, in an embodiment of the present disclosure, the dams230 disposed in the respective pixel regions EPA may have thesubstantially same capacity. Here, the term “substantially same” maymean that the dams 230 are designed or fabricated to have the same sizeor that sizes or capacities of the dams 230 are the same within a rangeincluding a variation belonging to an error occurs in a process. Forexample, the dams 230 disposed in the respective pixel regions EPA maybe fabricated to have the same sectional area and height.

To this end, one or more dams 230 having the substantially same size maybe disposed in each pixel region EPA, and the same number of dams 230may be provided in each pixel region EPA. That is, in some embodiments,accommodation capacities of the one or more dams 230 provided in thepixel region EPA may be the substantially same for each of the pixelregions EPA.

Thus, according to the embodiment of the present disclosure, amounts ofan LED solution coated in the unit light emitting regions EA of therespective pixel regions EPA can be controlled to be uniform. The amountof the LED solution coated in each unit light emitting region EA can bedirectly related to a number of bar type LEDs LD provided in the unitlight emitting region EA.

Thus, according to the embodiment of the present disclosure, in aprocess of injecting or scattering bar type LEDs LD into the unit lightemitting region EA of each pixel region EPA, an LED solution having auniform amount can be injected into each unit light emitting region EAthat is an effective light emitting region of each pixel region EPA.Accordingly, it is possible to provide a light emitting device thatimproves the coating (or distributing) uniformity of bar type LEDs LD,thereby achieving uniform luminance characteristics. Further, it ispossible to provide a light emitting device that easily controls thecoating (or distributing) region of bar type LEDs LD, thereby improvingvisibility.

FIG. 9 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region. In FIG. 9, components similar oridentical to the above-described embodiment are designated by likereference numerals, and their detailed descriptions will be omitted.

Referring to FIG. 9, the light emitting device according to theembodiment of the present disclosure may further include a filler 300provided in each pixel region EPA to fill in at least the dam 230, i.e.,at least the unit light emitting region EA. In some embodiments, thefiller 300 may include a plurality of scattering particles. For example,the filler 300 may include micro-particles 310 such as TiO₂ or silica.

According to the embodiment of the present disclosure, the dam 230surrounding each unit light emitting region EA is provided, so thatamounts of the filler 300 provided in the respective unit light emittingregions EA can be easily controlled. If the amounts of the filler 300are controlled, the coating uniformity of scattering particles 310coated or distributed in each unit light emitting region EA is improved,so that the visibility of the light emitting device can be entirelyuniformalized.

FIG. 10 is a plan view illustrating a unit region of a light emittingdevice according to an embodiment of the present disclosure, whichillustrates an individual pixel region. In FIG. 10, components similaror identical to the above-described embodiment are designated by likereference numerals, and their detailed descriptions will be omitted.

Referring to FIG. 10, the light emitting device according to theembodiment of the present disclosure may include a plurality of dams 230provided in a unit region, i.e., each pixel region EPA to be spacedapart from each other. For example, in an embodiment of the presentdisclosure, a plurality of unit light emitting regions, e.g., first tofourth unit light emitting regions EA1 to EA4, which are spaced apartfrom each other, may be provided in each pixel region EPA, and each ofthe first to fourth unit light emitting regions EA1 to EA4 may besurrounded by the dam 230.

That is, in an embodiment of the present disclosure, an effective lightemitting region of the individual pixel region EPA may be divided into aplurality of unit light emitting regions EA1 to EA4 having a fine size.In this case, a capacity of each of the dams 230 surrounding therespective light emitting regions EA1 to EA4, for example, may be smallas compared with the embodiment shown in FIG. 5.

According to the embodiment of the present disclosure, a variation incoating amount of an LED solution coated in the effective light emittingregions provided in each pixel region EPA, e.g., the first to fourthunit light emitting regions EA1 to EA4 can be further decreased.Specifically, the capacity of each dam 230 may be determined based on asize of the dam 230, i.e., a lateral length, a longitudinal length,and/or a height. In this case, a fabrication variation of the dam 230may be proportional to a size of the dam 230. For example, thefabrication variation (fabrication variation in a process related to thelateral length, the longitudinal length, the height, etc.) of the dam230 may be approximately 2% to 6% or so, which may be changed dependingon a material used to form the dam 230, process conditions, etc. Thus,as the size or capacity of the dam decreases, the variation in amount ofthe LED solution accommodated in the dam 230 may also decrease.

For example, the dam 230 of which lateral length, longitudinal length,and height are 100 μm, 100 μm, and 3 μm, respectively, may have acapacity of 30 pl, the dam 230 of which lateral length, longitudinallength, and height are 50 μm, 50 μm, and 3 μm, respectively may have acapacity of 7.5 pl, and the dam 230 of which lateral length,longitudinal length, and height are 25 μm, 25 μm, and 3 μm, respectivelymay have a capacity of 1.875 pl. In this case, when assuming that avariation in size or capacity of the dam 230, which may occur in afabricating process, is approximately 2%, a variation in capacity of thedam 230 having 30 pl may be about 0.6 pl, a variation in capacity of thedam 230 having 7.5 pl may be about 0.15 pl, and a variation in capacityof the dam 230 having 1.875 pl may be about 0.04 pl. That is, avariation in coating amount of the LED solution accommodated in eachunit light emitting region EA (or EA1 to EA4) of each pixel region EPAmay be determined according to the size of the dam 230 and/or thecapacity of the dam 230. The variation in coating amount of the LEDsolution may be continued to a variation in number of bar type LEDs LDprovided in each unit light emitting region EA (or EA1 to EA4). Thus, ifthe coating amount of the LED solution coated in each unit lightemitting region EA (or EA1 to EA4) decreases by decreasing the size ofthe dam 230, the variation in number of bar type LEDs LD provided in theunit light emitting region EA (or EA1 to EA4) of individual pixelregions EPA decreases.

If the variation in the fabricating process increases, the variation incoating amount of the LED solution corresponding to the capacity of thedam 230 may further increase. For example, when the variation in thefabricating process may be approximately 6%, the variation in capacityof the dam 230 having 30 pl may be about 1.8 pl, a variation in capacityof the dam 230 having 7.5 pl may be about 0.45 pl, and a variation incapacity of the dam 230 having 1.875 pl may be about 0.11 pl. Thus, whenassuming that the variation in the fabricating process is large, thecapacity of the dam 230 may decrease, so that it is possible toremarkably improve luminance non-uniformity caused by a variation innumber of bar type LEDs LD.

Meanwhile, in a light emitting device of a comparative example, in whichthe dam 230 is not provided, a coating amount of the LED solution coatedin each pixel region EPA may be determined according to a capacity ofthe barrier 240 and/or a one-time coating amount of a coating equipmentsuch as an inkjet head or nozzle. Therefore, the coating uniformity ofthe LED solution coated in each pixel region EPA may be in proportion tothe one-time coating amount and a variation in coating equipment. In thelight emitting device of the comparative example, in which the dam 230is not provided, it is difficult to minutely control the coating amountof the LED solution coated in each pixel region EPA, as compared withthe light emitting device according to the embodiment of the presentdisclosure. Hence, the one-time coating amount may be greater than anallowable amount. For example, when assuming that the variation incoating equipment is 5%, a variation in coating amount of the LEDsolution when the one-time coating amount of the LED solution is 50 plmay be 2.5 pl, and a variation in coating amount of the LED solutionwhen the one-time coating amount of the LED solution is 80 pl may be 4.0pl. That is, in the light emitting device of the comparative example,the variation in coating amount of the LED solution may be a remarkablylarge value as compared with the light emitting device according to theembodiment of the present disclosure. In order to decrease the variationin coating amount, it is advantageous to minimize the one-time coatingamount of the LED solution, but there may be a limitation in minimizingthe one-time coating amount of the LED solution due to a limitation of asize of the bar type LEDs LD and/or a coating equipment. For example,when a volume of each pixel region EPA defined by the barrier 240 is 60pl, an available one-time coating amount of the LED solution may beapproximately 50 pl to 80 pl, and there may be a limitation indecreasing the one-time coating amount of the LED solution to 50 pl orless due to the limitation of the size of the bar type LEDs LD and/orthe coating equipment.

Therefore, in the light emitting device of the comparative example, avariation in number of effective bar type LEDs LD disposed in the unitlight emitting region EA between pixel regions EPA may be large ascompared with the light emitting device according to the embodiment ofthe present disclosure. Accordingly, the light emitting device of thecomparative example exhibits non-uniform luminance characteristics.

That is, according to the above-described embodiments of the presentdisclosure, the dam 230 surrounding the unit light emitting region EA(or EA1 to EA4) is provided, so that the coating amount of the LEDsolution coated in each unit light emitting region EA (or EA1 to EA4)can be easily controlled. Accordingly, it is possible to provide a lightemitting device having uniform luminance characteristics.

FIGS. 11A to 11G are sectional views sequentially illustrating afabricating method of a light emitting device according to an embodimentof the present disclosure. FIGS. 12A and 12B are sectional viewsillustrating a coating amount of a bar type LED solution coated in anindividual pixel region according to an embodiment of the presentdisclosure. For more clearly describing the present disclosure, aplurality of unit regions are illustrated in FIG. 11A, but, forconvenience, only one unit region will be illustrated in FIGS. 11B to11G. In FIGS. 11A to 12B, detailed descriptions of the above-describedcomponents will be omitted.

Referring to FIG. 11A, a base substrate 200 is first prepared. In someembodiments, an insulating layer 201 may be formed on one surface of thebase substrate 200. In addition, a plurality of unit regions, e.g.,respective pixel regions EPA are defined on the base substrate 200, andsimultaneously, unit light emitting regions EA are defined in the pixelregions EPA. In some embodiments, one or more unit light emittingregions EA may be defined in each of the pixel regions EPA. Hereinafter,only one pixel region EPA will be described.

After that, as shown in FIG. 11B, at least one first electrode 210 andat least one second electrode 220 are formed in each of the unit lightemitting regions EA. In some embodiments, the first electrode 210 andthe second electrode 220 may be formed by forming and patterning aconductive layer on the one surface of the base substrate 200 on theinsulating layer 201. In some embodiments, the first electrode 210 andthe second electrode 220 may be simultaneously formed using the sameconductive material, or may be sequentially formed using the sameconductive material or different conductive materials.

After that, as shown in FIG. 11C, a dam 230 surrounding each of the unitlight emitting regions EA is formed, and a barrier 240 surrounding eachof the pixel regions EA is formed at the outside of the unit lightemitting regions EA to be spaced apart from the dam 230. In someembodiments, the dam 230 and the barrier 240 may be simultaneouslyformed, or may be sequentially formed. For example, the dam 230 may beformed first on the one surface of the base substrate 200 on which thefirst electrode 210 and the second electrode 220 are provided, and thebarrier 240 may be formed after forming the dam 230. However, thebarrier layer 240 may be formed first and the dam 230 may be formedafter forming the barrier layer 240. Alternatively, in anotherembodiment, at least one organic layer and/or at least one inorganiclayer, constituting the dam 230, may be formed, and simultaneously, atleast one organic layer and/or at least one inorganic layer,constituting the barrier 240, may be formed.

In some embodiments, the forming of the dam 230 may include performinghydrophilic treatment on a surface of the dam 230 to form a hydrophilicfilm 230 a. For example, the forming of the dam 230 may include forminga base pattern of the dam 230 by coating and patterning at least one ofone or more inorganic layers and one or more organic layers on the basesubstrate 200, and forming a hydrophilic film 230 a on the surface ofthe dam 230 by performing hydrophilic treatment on a surface of the basepattern.

In some embodiments, the forming of the barrier 240 may includeperforming hydrophobic treatment on a surface of the barrier 240. Forexample, the forming of the barrier 240 may include forming a basepattern of the barrier 240 by coating and patterning at least one of oneor more inorganic layers and one or more organic layers on the basesubstrate 200, and forming a hydrophobic film 240 a on the surface ofthe barrier 240 by performing hydrophobic treatment on a surface of thebase pattern.

In some embodiments, the base pattern of the dam 230 and/or the barrier240 may be formed through a sputtering process, a chemical vapordeposition (CVD) process, a dry etching process using plasma, a photoprocess, or the like. For example, when the dam 230 includes at leastone inorganic layer, the inorganic layer may be formed through thesputtering process, so that a height (H1 of FIG. 6) of the dam 230 canbe precisely controlled.

After that, as shown in FIG. 11D, a nozzle (or outlet) 400 of a coatingequipment is disposed on each of the unit light emitting regions EA, andan LED solution 410 in which a plurality of bar type LEDs LD aredispersed is coated or dropped in the unit light emitting regions EA.Accordingly, the bar type LEDs LD may be injected into each of the unitlight emitting regions EA. That is, in some embodiments, the bar typeLEDs LD may be injected into each of the unit light emitting regions EAusing an inkjet printing technique or the like. However, the method ofinjecting the bar type LEDs LD is not limited thereto. In someembodiments, the LED solution 410 may have an ink or paste phase. Asolvent of the LED solution 410 may include a photo resist or organiclayer containing the solvent, but the present disclosure is not limitedthereto. In some embodiments, the solvent may be a volatile solvent.

At this time, as shown in FIG. 11E, the LED solution 410 is coated tofully fill in at least each of the unit light emitting regions EA. Thatis, in an embodiment of the present disclosure, the LED solution 410 ofwhich amount is equal to greater than a capacity of the dam 230 iscoated in each of the pixel region EPA. Accordingly, the amount of theLED solution 410 coated in each of the unit light emitting regions EAcan be controlled to be uniform.

In some embodiments, a one-time coating amount of the LED solution 410may be set to be equal to or greater than the capacity of the dam 230,and may be set to be equal to or less than a total accommodation amountof the individual pixel region EPA (a total accommodation amount by thedam 230 and the barrier 240). For example, when the capacity of the dam230 is 10 pl, and the total accommodation amount of the individual pixelregion EPA is 60 pl, the one-time coating amount of the LED solution 410may be set to 10 pl to 60 pl.

For example, in some embodiments, as shown in FIG. 12A, the LED solution410 of which capacity approximately corresponds to the totalaccommodation amount of the individual pixel region EPA may be coated tofully fill in the individual pixel region EPA. Here, if the barrier 240has hydrophobicity, the LED solution 410 can be prevented to a certaindegree from overflowing into an adjacent pixel region EPA, etc.Meanwhile, in some embodiments, as shown in FIG. 12B, the LED solution410 of which amount is smaller than the total accommodation amount ofthe individual pixel region EPA may be coated. At this time, if thecoating amount of the LED solution 410 is equal to or greater than thecapacity of the dam 230, only the LED solution 410 having a certainamount corresponding to the capacity of the dam 230 is coated oraccommodated. That is, according to the embodiment of the presentdisclosure, although a variation in coating amount of the LED solution410 occurs, the amount of the LED solution 410 coated in each of theunit light emitting region EA can be controlled to be uniform.

After the LED solution 410 is coated in each of the pixel region EPA orat the same time when the LED solution 410 is coated, an electric fieldis induced by applying a voltage between the first electrode 210 and thesecond electrode 220 as shown in FIG. 11F. Accordingly, the bar typeLEDs LD that are randomly dispersed in the LED solution 410 may bealigned. For example, as a DC or AC voltage is applied between the firstelectrode 210 and the second electrode 220, self-alignment of at leastone bar type LED LD injected in the unit light emitting region EA may beoccurred such that both ends of the bar type LED LD are located on thefirst electrode 210 and the second electrode 220, respectively. Morespecifically, if a voltage is applied to the first electrode 210 and thesecond electrode 220, bipolarity is induced to the bar type LED LD by anelectric field formed between the first electrode 210 and the secondelectrode 220. Accordingly, the bar type LED LD is self-aligned betweenthe first electrode 210 and the second electrode 220.

After that, as the solvent of the LED solution 410 is removed, a lightemitting device may be fabricated as shown in FIG. 11G. In anon-restrictive embodiment in which the solvent of the LED solution 410is removed, the solvent of the LED solution 410 may be removed by usinga solvent of a volatile material and volatilizing the solvent.

Meanwhile, in some embodiments, the light emitting device may furtherinclude a filter 300 in which a plurality of scattering particles 310are scattered as shown in FIG. 9. In this case, after the solvent of theLED solution 410 is removed, coating (or dropping) of the filter 300including the scattering particles 310 in the pixel regions EPA may befurther performed.

At this time, the filler 300 of which amount is equal to or greater thanthe capacity of at least the dam 230 is coated in each of the pixelregions EPA, so that it is possible to control amounts of the filler 300provided in the respective unit light emitting regions EA to be uniformand to improve the visibility of the light emitting device.

FIGS. 13A and 13B are plan views illustrating a luminance uniformityeffect according to an embodiment of the present disclosure. Morespecifically, FIG. 13A illustrates one region of the light emittingdevice of the comparative example, and FIG. 13B illustrates one regionof the light emitting device according to the embodiment of the presentdisclosure. For convenience, in FIG. 13A, positions having the highestluminance and relative sizes of the luminances are represented aspositions and size of circles, respectively.

Referring to FIG. 13A, in the light emitting device of the comparativeexample, in which the dam 230 is not provided, positions having thehighest luminance, i.e., positions SP at which bar type LEDs LD areconcentrated, are randomly distributed. Also, in the light emittingdevice of the comparative example, non-uniform luminance characteristicsare shown for each pixel region EPA.

On the other hand, as described above, in the light emitting deviceaccording to the embodiment of the present disclosure, the dam 230 isformed in each of the pixel regions EPA, so that it is possible toeasily control the region in which the effective bar type LEDs LDcapable of emitting light by being aligned between the first and secondelectrodes 210 and 220, and to control the density of the effective bartype LEDs LD to be uniform. Thus, in the light emitting device accordingto the embodiment of the present disclosure, as shown in FIG. 13B,positions having the highest luminance, i.e., the positions SP at whichthe bar type LEDs LD are concentrated, are controlled to be uniform, anduniform luminance characteristics are shown without any large variationof luminance for each pixel region EPA.

According to the present disclosure, it is possible to control luminancecharacteristics to be uniform and to improve visibility of the lightemitting device including the bar type LEDs.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present disclosure asset forth in the following claims.

What is claimed is:
 1. A light emitting device comprising: a basesubstrate including a light emitting region; a dam formed of aninsulating material, spaced from two opposite edge sections of the basesubstrate, disposed between the two opposite edge sections of the basesubstrate, disposed on the base substrate, and defining the lightemitting region; a first electrode disposed on the light emittingregion; a second electrode disposed on the light emitting region, thesecond electrode spaced apart from the first electrode; LEDs disposed onthe light emitting region and electrically connected to one or more ofthe first electrode and the second electrode; and a third electrodedisposed on the light emitting region and directly contacting at leastone of the first electrode and the second electrode.
 2. The lightemitting device of claim 1, wherein one LED of the plurality of LEDs iselectrically connected to one of the first electrode and the secondelectrode by the third electrode.
 3. The light emitting device of claim1, further comprising: a fourth electrode disposed in the same layer asthe third electrode and spaced apart from the third electrode; whereinthe third electrode is in contact with a first end of at least one ofthe LEDs, and wherein the fourth electrode is in contact with a secondend of the at least one of the LEDs.
 4. The light emitting device ofclaim 1, wherein a length of each of the LEDs is equal to or greaterthan a shortest length between the first electrode and the secondelectrode.
 5. The light emitting device of claim 4, wherein a first endand a second end of at least one of the LEDs are disposed on the firstelectrode and the second electrode, respectively, and wherein the thirdelectrode is disposed on one of the first end and the second end of theat least one of the LEDs.
 6. The light emitting device of claim 1,further comprising a barrier on the base substrate and surrounding thedam, and wherein the dam is spaced apart from the barrier.
 7. The lightemitting device of claim 6, wherein at least a surface of the dam hashydrophilicity.
 8. The light emitting device of claim 6, wherein atleast a surface of the barrier has hydrophobicity.
 9. The light emittingdevice of claim 6, wherein a height of the dam is equal to or greaterthan that of the barrier.
 10. The light emitting device of claim 1,wherein at least one region of at least one of the first and secondelectrodes overlaps the dam in a plan view.
 11. The light emittingdevice of claim 1, wherein the dam is configured as a closed sidewall ofwhich at least one region has a flat or curved surface.
 12. The lightemitting device of claim 1, further comprising a filler provided in thelight emitting region to fill in at least the dam, the filler includingscattering particles.
 13. A light emitting device comprising: a basesubstrate including light emitting regions spaced apart from oneanother; at least one dam formed of an insulating material, spaced fromtwo opposite edge sections of the base substrate, disposed between thetwo opposite edge sections of the base substrate, disposed on the basesubstrate, and defining the light emitting regions; pixels respectivelyprovided on the light emitting regions of the base substrate, whereineach of the pixels comprises: first electrodes; second electrodes spacedapart from each of the first electrodes; LEDs each electricallyconnected to one of the first electrodes and one of the secondelectrodes; and third electrodes each directly in contact with at leastone of the first electrodes or at least one of the second electrodes.14. The light emitting device of claim 13, wherein one of the thirdelectrodes is in contact with a first end of at least one of the LEDs,and wherein another of third electrodes is in contact with a second endof the at least one of the LEDs.
 15. The light emitting device of claim13, wherein the first electrodes are electrically connected to eachother, and the second electrodes are electrically connected to eachother.
 16. The light emitting device of claim 13, wherein the firstelectrodes and the second electrodes are disposed in the same layer, andwherein one of the first electrodes and one of the second electrodes aredisposed to form a pair such that at least one region of the one of thefirst electrodes and at least one region of the one of the secondelectrodes are opposite to each other.
 17. The light emitting device ofclaim 16, wherein the first electrodes and the second electrodes arealternately disposed.
 18. The light emitting device of claim 13, whereinat least one dam include dams respectively surrounding the lightemitting regions, wherein the dams have the same height.
 19. A lightemitting device comprising: a base substrate including a light emittingregion; a dam disposed on the base substrate and defining the lightemitting region; a first electrode disposed on the light emittingregion; a second electrode disposed on the light emitting region andspaced from the first electrode; LEDs disposed on the light emittingregion and electrically connected to one or more of the first electrodeand the second electrode; a third electrode disposed on the lightemitting region and directly contacting at least one of the firstelectrode and the second electrode; and a barrier disposed on the basesubstrate, spaced from the dam, and surrounding the dam.